Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
1101 AM EST Sat Nov 13 2021
Valid 12Z Tue Nov 16 2021 - 12Z Sat Nov 20 2021
...Overview and Guidance/Predictability Assessment...
A progressive flow regime, with troughing amplifying mid-continent
Wednesday and next Saturday, will be seen this period. While
detail issues remain, the 06z GFS/00z ECMWF/00z UKMET fit best
with the ensemble means, with the 00z Canadian falling out of
favor as early as Wednesday with its more progressive flow
pattern. With some amplification expected at times, quicker does
not seem best. The pressures, precipitation forecast, winds, and
500 hPa heights were primarily derived from the 06z GFS, 00z
UKMET, 00z ECMWF, and the 00z NAEFS/ECMWF ensemble means. The
remainder of the grids relied heavily on the 13z National Blend of
Models guidance.
...Weather/Hazards Highlights...
Expect mostly light to moderate rain and higher elevation snow
over the northern Rockies early Tuesday in association with the
upper trough/leading cold front pushing through the region before
fading. The potent surface low tracking across southern Canada
Tuesday onward will bring a period of strong/gusty winds to
northern tier areas, especially the Northern Plains on Tuesday
into Wednesday. Moisture should increase ahead of the low's
trailing cold front from midweek onward, leading to mostly
light/moderate rain over portions of the Mississippi, Ohio, and
Tennessee Valleys along with some light precipitation in the Great
Lakes region. The southern Florida Peninsula should increasing
rainfall mid-late week as moisture interacts with a stalled front
to the south. Some precipitation should reach the West late week,
but for the moment only modest amounts are expected. The Midwest
should see moderate precipitation late Friday-Saturday as the
western system sweeps eastward.
Well above normal temperatures will continue into Tuesday over the
Plains and southern half of the West. The warmest readings versus
normal should be over the Plains where plus 15-25F anomalies will
be common and some daily records for highs/warm lows will be
possible. Currently the best potential for highs to approach/reach
record values is over the western half of Texas. As the cold front
emerging from the Northeast continues onward, warmth will extend
into the South and East Wednesday-Thursday but in modified form
with highs/lows generally only up to 10-15F above normal. Cooler
air behind the front will spread mostly 5-10F below normal
temperatures across the central and eastern U.S. from Wednesday
through the rest of the week.
Roth/Rausch/Tate
Additional 3-7 Day Hazard information can be found on the WPC
medium range hazards outlook chart at:
https://www.wpc.ncep.noaa.gov/threats/threats.php
WPC medium range 500mb heights, surface systems, weather grids,
quantitative precipitation, winter weather outlook probabilities
and heat indices are at:
https://www.wpc.ncep.noaa.gov/medr/5dayfcst500_wbg.gif
https://www.wpc.ncep.noaa.gov/medr/5dayfcst_wbg_conus.gif
https://www.wpc.ncep.noaa.gov/5km_grids/5km_gridsbody.html
https://www.wpc.ncep.noaa.gov/qpf/day4-7.shtml
https://www.wpc.ncep.noaa.gov/wwd/pwpf_d47/pwpf_medr.php?day=4
https://www.wpc.ncep.noaa.gov/heat_index.shtml